Drugs affecting breast milk and lactation

1. Drugs affecting breast milk and lactation Prof. Hanan Hagar Pharmacology Department College of Medicine

2. Learning issues Student should be able to : • Recognize the main pharmacological characters that control the passage of drugs from milk to baby. • Identify the adverse effects of major pharmacological categories on babies. • Know drugs that can inhibit lactation and should be avoided in breast feeding • Know drugs that may enhance lactation. • Describe the best and safest medication to be given to breast feeding women if she is suffered from different diseases as epilepsy, infection, diabetes, heart failure, hypertension.

3. LACTATION • Breast feeding is very important because breast milk is the healthiest form of milk for babies. • Provide the baby with immunoglobulins (IgA, IgM) that are essential for protection against gastroenteritis.

4. DRUGS AND LACTATION • Most drugs administered to breast feeding woman are detectable in milk. • The concentration of drugs achieved in breast milk is usually low (< 1 %). • However, even small amountsof some drugs may be of significance for the suckling child. • There are many pharmacokinetic and pharmacodynamics changes in pediatrics.

5. Pediatric population are classified into: • Newborn:less than one month old • Preterm neonates: born before38 weeksof pregnancy • Full-term neonates:38-42 weeksof gestational age • Infants (babies):1 month – 12 months of age • Children: 1 -12 years of age • Toddler (young child):1-5 years • Older child: 6-12 years • Adolescent:13-18 years

6. Pharmacokinetics changes in pediatrics • Higher gastric pH • Higher concentrations of free drug (due to reduced serum albumin and its binding capacity). • Higher percentage of body water • Lower rate of metabolism due to immaturity of liver enzymes. • Renal clearance is less efficient: (Renal blood flow-  GFR). • Premature babies have much more limited capacity for metabolism and excretion.

7. Molecular weight Lipid solubility Degree of ionization Drug pH Protein binding Half life Oral bioavailability Factors controlling passage of drugs into breast milk Factors related to drugs :

8. Factors related to mother • Dose of the drug • Route of administration • Time of breast feeding • Health status • Maternal drug concentration

9. Factors related to neonates • Age • Body weight • Health status

10. Factors controlling passage of drugs into breast milk Molecular weight: low molecular weight drugs are more likely to be transferred to breast milk than high molecular weight E.g. Insulin: MW > 6,000 daltons Heparin: MW 40,000 daltons Ethanol: MW 200

11. Monoclonal antibodies, pass very poorly into milk after the first 1st week postpartum. • The epithelium of the breast alveolar cells is most permeable to drugs during the 1st week postpartum, so drug transfer to milk may be greater during the 1st week of an infants life.

12. Factors controlling passage of drugs into breast milk 2. Lipid solubility of the drug:lipid soluble drugs pass more freely in the breast milk 3. Degree of ionization: Ionized form of drugs are less likely to be transferred into breast milk. e.g. heparin passes poorly into breast milk.

13. 4. pH of drug: pH of milk is slightly more acidic than maternal blood. Weak basic drugs tend to concentrate in breast milkand become trapped secondary to ionization. Weak acidic drugs don't enter the milk to a significant extent and tend to be concentrated in plasma.

14. pH of the plasma and milk Maternal blood circulation Milk Milk pH is 7.2 More acidic plasma pH is 7.4 Ionized alkaline drug will be captured Alkalinedrug Nonionized acidic drug will diffuse back Acidic drug

15. 5. Plasma protein binding of drugs Drugs circulate in maternal circulation in unbound (free) or bound forms to albumin. Only unbound form gets into maternal milk. Definition of good protein binding > 90% e.g. warfarin 6. Half life of drug Avoid the use of drugs with long half lives short half life (t ½) are preferable. Oxazepam vs diazepam

16. Volume of distribution Transfer of drug from maternal blood to milk is low with drugs that have large volume of distribution (Vd).

17. Factors related to mother • Dose of the drug • Route of administration • Time of breast feeding • Health status • Maternal drug concentration

18. Factors related to mother Route of administration • Route of administration affect the concentration of the drug in maternal blood. • Maternal use of topical preparations (creams, nasal sprays or inhalers) are expected to carry less risk to a breastfed infant than systemically administered drugs.

19. Factors related to mother Time of breastfeeding • The concentration of the drug in the milk at the time of feeding. • Lactating mother should take medication just after nursing and 3-4 hours before the next feeding. (to allow time for drug to be cleared from the mother’s blood – drug concentration in milk will be low).

20. Factors related to neonates • Age • Body weight • Health status

21. The amount of a drug to which the baby is exposed as a result of breast feeding depends on: • The amount of milk consumed. • The amount of drug absorbed from GI. • The ability of the baby to eliminate the drug.

22. Age & Health status Special cautions are required in - Premature infants - Low birth weight - Infants with G6PD deficiency - Infants with impaired ability to metabolize /excrete drugs e.g. hyperbilirubinemia.

23. Drugs contraindicated during lactation Only few drugs are totally contraindicated Anticancer drugs Doxorubicin, cyclophosphamide, methotrexate Radiopharmaceuticals e.g. radioactive iodine CNS acting drugs amphetamine, heroin, cocaine Lithium Chloramphenicol

24. Drugs that can suppress lactation These drugs reduce prolactin Levodopa (dopamine precursor) Bromocriptine(dopamine agonist). Estrogen, combined oral contraceptives that contain high-dose of estrogen and a progestin. Androgens Thiazide diuretics

25. Drugs that can augment lactation Dopamine antagonists : they stimulate prolactin secretion galactorrhea e.g. Metoclopramide (antiemetic) Domperidone (antiemetic) Haloperidol (antipsychotic) Methyl dopa (antihypertensive drug) Theophylline (used in asthma)

26. Antibiotics

27. Antibiotics

28. Sedative/hypnotics single doses are unlikely to be harmful Regular use of high doses should be avoided

29. Antidiabetics

30. Oral contraceptives

33. Drugs of choice in lactation

34. Summary for choice of drugs The safest drug should be chosen. E.g. Acetaminophen than aspirin for analgesia. Route of administration (topical, local, inhalation) instead of an oral form. Short acting Highly protein bound Low lipid solubility High molecular weight Poor oral bioavailability No active metabolites well-studied in infants

35. General considerations • Infants should be monitored for adverse effects e.g. feeding, sedation, irritability, rash, etc. • Drugs with no safety data should be avoided or lactation should be discontinued

36. General considerations • Do not guess • Use the following sources: • Use Medication and Mothers’ Milk (www.iBreastfeeding.com) • Use lactmed or toxnet (http://toxnet.nlm.nih.gov ) a free online database with information on drugs and lactation, is one of the newest additions to the National Library of Medicine's TOXNET system, a Web-based collection of resources covering toxicology, chemical safety, and environmental health.